package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.CACHE_SHOP_KEY;
import static com.hmdp.utils.RedisConstants.LOCK_SHOP_KEY;

@Slf4j
@Component
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }
    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit) {
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(unit.toSeconds( time))));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    public <R, ID> R queryWithPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback,Long time, TimeUnit unit
    ){
        String key=keyPrefix+id;
        //1.从redis查询店铺
        String Json = stringRedisTemplate.opsForValue().get(key);
        //2.判断店铺是否存在
        if(StrUtil.isNotBlank(Json)){
            //3.存在，返回
            return JSONUtil.toBean(Json, type);
        }

        if (Json != null ) {
            return null;
        }
        //实现缓存重建
        //1.获取互斥锁
        R r = dbFallback.apply(id);
            //5.判断店铺是否存在
            if (r == null) {
                //6.不存在，写入空值
                stringRedisTemplate.opsForValue().set(key, "", 2L, TimeUnit.MINUTES);

                return null;
            }
            //6.存在，写入redis
this.set(key, r, time, unit);
        //7.存在，返回店铺
        return r;
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);
    public <R,ID> R queryWithLogicalExpire(String keyPrefix,ID id,Class<R> type,Function<ID,R> dbFallback,Long time, TimeUnit unit){
        String key=keyPrefix+id;
        //1.从redis查询店铺
        String Json = stringRedisTemplate.opsForValue().get(key);
        //2.判断店铺是否存在
        if(StrUtil.isBlank(Json)){
            //3.存在，返回
            return null;
        }
        //4.命中，需要先把json反序列化成对象
        RedisData redisData = JSONUtil.toBean(Json, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();

        R r = JSONUtil.toBean(data, type);;
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1未过期，返回店铺信息
            return r;
        }
        //5.2过期，需要缓存重建
        //6.缓存重建
        //6.1 获取锁
        String lockKey=LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        //6.2判断是否获取锁成功
        if (isLock){
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    R r1 = dbFallback.apply(id);
                    this.setWithLogicalExpire(key, r1, time, unit);
                }catch (Exception e){
                    throw new RuntimeException(e);
                }finally {
                    unlock(lockKey);
                }
            });
        }
        //6.3获取锁成功， 开启独立线程进行缓存重建
        //6.4返回过期的商铺信息
        return r;
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

}
